研究進展
Led light boxes for standardized lighting of coloured stones and diamonds
In the past, coloured gemstones and diamonds were often examined in natural daylight, but reproducing such specific lighting conditions was challenging. Some impractical methods had been suggested, li
At the frontier of research: irradiation experiments on corundum
As is known in the gem trade, the colour of certain gems may be caused or influenced by the presence of colour centres (a type of defect in the crystal structure that can absorb light and thus result
Purple love
It is always a pleasure for our team to analyse gemstones which are not so common, or sometimes even very rare, but which may compete in beauty and quality (but often not in hardness) with the most pr
Dark purple chrysoberyl
Since about three years, we see at SSEF occasionally chrysoberyl samples of very dark purplish to purplish brown colour, sometimes of quite impressive size (>10 ct). Based on chemical composition, the
Jadeite: impregnated and dyed
Jadeite-jade of saturated emerald green colour is highly valued in Asia. It is therefore not astonishing to see in the market either heavily treated jadeite-jade or even imitations made of different m
Saturation too low for Paraiba tourmaline
Copper-bearing tourmaline, also known as Paraiba tourmaline in the trade, may come in a range of colours from blue to green. Similarly, the colour saturation of such copper-bearing tourmalines may var
A perfect match: Paraiba tourmaline and Indicolite tourmaline
A few months ago, a client submitted to SSEF two tourmalines of attractive and matching shape, size and colour, both supposedly being Paraiba tourmalines (Figure 1). Chemical analyses and absorption s
Blue surprise: apatite and not Paraiba tourmaline
Last summer, the SSEF received a series of nine small blue cabochons ranging in weight from 0.4 to 1.5 ct. The client assumed that these stones were Paraiba tourmalines from a very early production of
An interesting chrysoberyl-alexandrite combination
The mineral chrysoberyl BeAl2O4 is an attractive gemstone that shows a wide variation of colours mostly ranging from yellow to green and brownish green to dark brown. These colours are mainly due to t
Dyed quartz imitating emerald
From time to time, we receive some oddities for testing, such as the rough “emerald”, reportedly originating from Africa and submitted by a client for testing. Already a quick visual examination m
Happy hour with soda and lime: glass imitating coral
Recently, a necklace was submitted to SSEF for coral testing. Already a first microscopic inspection revealed that this item in fact consisted of numerous tiny glass beads, visually imitating coral ve
Novel Coral-ID method used on samples seized by swiss customs
In 2022, an international research group led by scientists from the Swiss Gemmological Institute SSEF and the University of Zurich’s Institute of Forensic Medicine (IRM) reported a breakthrough in p
Saltwater pearl with barium
Recently, the SSEF received a button-shaped pearl of 7.5 ct for testing. Based on X-ray radiography and a UV-Vis-NIR reflectance spectrum, the pearl was easily identified as a saltwater natural pearl
Cultured pearl with unconventional bead material
Recently, we received a round pearl for testing which exhibited an excellent surface quality and a remarkable size of 24 mm in diameter. Interestingly, its weight of 60 ct was rather low for such a pe
Assembled blisters and shells used to imitate pearls
Since historic times, natural pearls have been treasured and considered symbols of wealth and beauty. When harvesting (natural) pearls, one may find not only a pearl inside a shell, but also blister p
Pearls & diamonds: a royal selection
The SSEF is known worldwide as a leading authority in gem testing, and as such we have the great pleasure to scientifically analyse some of the most prestigious and important jewellery before it is of
Queen Mary pearl: age dating & DNA fingerprinting
Similar to gemstones which are re-polished over time and thus need an updated SSEF report, we also occasionally receive pearls a second or third time for a new report, for example when the pearl is se
The value of cultured pearls: evolution and current trends
Pearls are often reported as the oldest valuable gem known to humankind, and have been collected for at least 8,500 years (Ainis, et al., 2019). Natural pearls are accidental formations in wild oyster